Domain I, Topic A, #2A

Domain I, topic A, #2a

Food Microbiology

Background-

1. Kinds of bacteria

·  harmless bacteria, which accounts for the majority of bacteria, and are of no concern for food safety.

·  beneficial bacteria

- intestinal, which aid digestion and produce nutrients.

- those used in food production like cheese, yogurt, and sauerkraut.

·  undesirable bacteria, which cause food spoilage (souring/decomposition), may or may not cause disease, & are evident by smells, stickiness, discoloration, and slime of foods.

(Spoilage is a sign of improper handling and/or storage & can be costly)

·  disease-causing bacteria, which cause food-borne illness, will not necessarily leave an odor or taste, and can be prevented through; Proper hygiene, sanitary food handling and proper storage techniques.

2. Bacterial growth

·  conditions include the need for:

- food (protein, nutrients)

- moisture, and temps between 40-140 degrees F,

- acid or basic pH environment,

- possibly oxygen,

- time (bacteria need time to adjust to new environments).

·  potentially hazardous foods:

- animal food products

- any plant based food that has been cooled or partially heated

3. Ways bacteria spread

·  hands

·  cough/sneeze

·  other foods

·  equipment/utensils

·  air/water

·  insects/rats/mice

4. Protection against bacteria

·  keep bacteria from spreading by keeping food surfaces clean/sanitized, & protecting food from air exposure.

·  stop bacteria from growing by removing conditions for growth (refrig/heat).

·  kill bacteria by exposing to temperatures of 170 degrees F for 30 sec, or chemical sanitizers.

Sources of food contamination and spoilage

1.  Personal Hygiene

·  Most food-borne disease is caused by bacteria spread by food workers.

·  Prevention:

- don’t work with food if you have a communicable disease or infection

- bathe or shower daily

- wear clean uniforms and aprons

- keep air neat and clean- always wear a hat or hair net

- keep mustaches and beards trimmed and clean

- wash hands regularly for 20 sec. and up to mid arm.

- cover cough/sneeze and then wash hands

- don’t smoke or chew gum while working with food

- cover cuts or sores with clean bandages

- don’t sit on food surfaces

2.  Food Handling and Preparation-

• Two major problems exist when handling and preparing food:

-  cross-contamination

-  food is usually between 40 degrees F- 140 F (bacterial growth zone).

• Rules :

-  start w/ clean, wholesome foods

-  handle foods as little as possible

-  use clean, sanitized equipment and counters

-  after handling raw foods, clean and sanitize these items

-  clean as you go

-  wash raw fruits and veggies

-  when taking foods from refrig, don’t bring out more than can be processed in one hour

-  keep foods covered whenever possible

-  don’t let any perishable foods remain in the temp range prime for bacterial growth for more than one hour

-  boil leftover gravies, sauces, and soups before re-use

-  don’t mix leftovers w/ freshly prepared foods

-  chill all ingredients for protein or starch salads before combining

-  chill quickly be using swallow pans

-  cook all pork products to an internal temp of 150 F

3. Cleaning and sanitizing equipment

• definitions:

-  cleaning = removing visible soil

-  sanitizing = killing disease-causing bacteria

Ø  heat- can penetrate small cracks and crevices, is non-corrosive to metal, non-selective to microbial groups, leaves no residue, and is easily measurable

Ø  chemicals- chlorine (50 ppm @ 75 degree F for 1 min.), iodine (12.5 ppm @ 72 F for 1 min), and quaternary ammonia (220 ppm @ 75 F for 1 min. & not effective in hard water); they kill a wide range of microorganism, deodorize and sanitize items, are non-toxic to humans @ appropriate concentrations (listed by ppms) colorless/non-staining, easy to handle, must come in direct contact w/ microbe, some are selective, need specific [], temps, pH, and time of exposure.

• factors affecting cleaning efficiency

-  types of soil to be removed

-  water quality

-  the detergent or cleaner to be used

-  water temp

-  water velocity

-  time detergent remain in contact w/ surface

-  the [] of the cleaner

• cleaning and sanitizing stationary equipment

-  unplug

-  disassemble when possible

-  wash all food contact surfaces using detergent and clean cloths

-  sanitize all surfaces

-  allow to air dry

-  reassemble equip.

4. Food storage- Two purposes to the rules that follow: to prevent contamination of foods & to prevent growth of bacteria that may already by in foods.

·  Perishable food should by kept at <40 degrees F OR >140 degrees F.

·  Dry storage- don’t pertain to foods that are likely to support bacterial growth in their normal state.

- store dry foods in a cool, dry place, off the floor (min 6 inches) away from the wall and not under a sewer (or water) line.

- keep all containers tightly closed.

·  Freezer storage:

-  keep all frozen foods @ < 0 degrees F.

-  keep tightly wrapped or packaged to prevent freezer burn

-  label and date all items

-  thaw foods properly- in refrig or under cold running water

·  Refrigerator storage

-  keep all perishables properly refrig

-  don’t overload refrig

-  keep doors closed and shelves clean

-  store raw foods and cooked foods separately

-  always keep cooked foods above raw foods

-  keep refrig foods wrapped or covered in a sanitary container

-  don’t let any unsanitary surface touch any foods

-  chill foods as quickly as possible over ice or in a cold-water bath before placing in refrig ( hot stock right off range may take 10 hrs to cool to 40 degrees F)

-  when holding cold foods in an ice bath for service, don’t fill above the edge of the container

• Hot Food storage

-  to keep foods hot for service, use steam tables or other equipment that will keep the foods above 140 F

-  keep foods covered

-  bring foods up to temperature before placing on steam table

-  don’t let ready to eat foods come in contact w/ any contaminated surfaces

5.  Rodent & Insect Control

• rats, mice, flies, and cockroaches can spread disease by contaminating food and food contact surfaces

• block them out

-  block all possible rodent entrances including structural defects in

the building

-  put screens on all windows and doors

-  make sure all doors are self-closing or contain an air curtain

-  inspect incoming supplies for signs of insect infestation

• eliminate harborage and breeding places

-  repair holes in walls and floors

-  eliminate narrow spaces between and behind equipment

-  store food and food supplies off of the floor (> 6 inches)

-  seal all cracks and crevices

-  remove all fly breeding places and items ( i.e. garbage, manure, general filth)

• eliminate food supplies

-  keep all foods tightly covered or wrapped

-  keep garbage container tightly covered clean up all spoiled food

-  general sanitation

• exterminate regular